The present invention relates to a cleaning composition, and a cleaning method that utilizes the cleaning composition.
Chemical mechanical polishing (CMP) has spread rapidly as a planarization technique used when producing a semiconductor device, for example. CMP is a technique that causes the polishing target and a polishing pad to come in sliding contact with each other while pressing the polishing target against the polishing pad, and supplying a chemical mechanical polishing aqueous dispersion to the polishing pad to chemically and mechanically polish the polishing target.
Along with a recent remarkable increase in the degree of integration of a semiconductor device, even contamination with a trace amount of impurities may significantly affect the performance of the device, and the yield of the product. For example, when an 8-inch wafer has been subjected to CMP, 10,000 or more particles having a particle size of 0.2 micrometers or more are present on the surface of the wafer. It has been desired to remove such particles by cleaning so that only several to several dozen particles remain on the surface of the wafer. The surface concentration of metal impurities (i.e., the number of impurity atoms per square centimeter) is 1011 to 1012 or more. It has been desired to remove such metal impurities by cleaning so that the surface concentration of metal impurities is reduced to 1×1010 or less. Therefore, a cleaning step that is performed after CMP is indispensable when applying CMP to production of a semiconductor device.
A wiring board included in a semiconductor device includes a wiring material, and a barrier metal material that prevents diffusion of the wiring material into an inorganic material film. Copper or tungsten has been mainly used as the wiring material, and tantalum nitride or titanium nitride has been mainly used as the barrier metal material. For example, when copper and tantalum nitride or titanium nitride are present on the surface of the wiring board, it is necessary to remove a copper oxide film and an organic residue on the surface of the wiring board without causing corrosion of the wiring material and the barrier metal material. Therefore, an acidic cleaning agent that can suppress corrosion of the barrier metal material has been normally used (see JP-A-2010-258014, for example).
The width of a copper wire has been reduced when using a 20 nm node semiconductor substrate, for example, and cobalt that exhibits high adhesion to copper and can form a thin film has been used instead of a known barrier metal material. However, cobalt is easily eluted under acidic conditions, and occurrence of pits due to the acidic solution significantly affects yield when the width of a copper wire is reduced. In recent years, a neutral to alkaline cleaning agent has been used in order to deal with the above problem (see JP-A-2009-055020, for example).